(a) Field of the Invention
The present invention relates to a precision driver rotation structure, and more particularly, to a driver incorporated with a differential gear mechanism for easier and steady rotation.
(b) Description of the Prior Art:
Screwdrivers generally available in the market come highly diversified either in type or size. Force applied varies depending on the size of the screwdriver. For easier operation, ratchet is incorporated in the screwdriver used to set the driver for counter-clockwise or clockwise rotation or in both directions. However, a precision driver dedicated for minute screws needs only minimum force to be applied. In addition, the structure of the driver tends to be compact, leaving not much space to accommodate comparatively complicate clockwise or counter-clockwise ratchet mechanism while such ratchet mechanism is not necessarily required for the precision driver. Therefore, most of the precision drivers relate to a shank having one end fixed with a blade and the other end pivoted with a bonnet. In use, only one hand of the user is sufficient to tighten or loosen up a screw. The user has his/her index finger pressing against the bonnet and with other fingers of the same hand holding the shank to point the blade tip in the head of the screw to rotate the shank using the bonnet as a support axis.
However, said precision driver operates by directly rotating the shank to screw or unscrew with the blade. The driving itself is vulnerable to shaking and it is difficult for the blade to stick to the head of the screw while the rotation by the thumb in conjunction with the other three fingers may become very awkward. Therefore, the operation of the prior art of the precision driver is not so handy and further improvement is justified.
The primary purpose of the present invention is to provide a precision driver rotation structure. It is essentially composed of a knob on top of the driver, a differential gear mechanism below for transmitting the torque from the knob to driver a shank rotating in the same direction and a handle cladding the shaft to secure a firm grip of the driver.
To achieve the purpose, said handle relates to a hollow tube having at its top provided with a containing base, a circular space of accommodation is formed inside the containing base, and the inner wall of said containing base is provided with meshing gears, the lower end of the tube has a bushing. A blade is formed at the tip of the shank which penetrates the handle and the bushing. An axial block formed in one piece with a gear is provided at the upper shank with the shank penetrating through said axial block and gear. A rotation plate having multiple axial holes is pivoted and holding against the gradation of the axial block and the gear. A pivoting knob is mounted to the upper opening of the containing base having below it pivoted at equal distance at least three planet gears. The planet gears are located at where between the gear and the meshing gear on the inner wall of the containing base and placed into said meshing gear while each axis of said planet gears penetrates through the axial hole of said rotation plate. An axial hole containing a rolling ball is provided in the center at the base of the knob to receive the insertion of the upper shank that protruding from the gear; consequently, when the handle is held with the tip of the blade pressing a screw to rotate the head of the screw, said planet gears rotate against and voluntarily rotate surround the meshing gear on the inner wall of the containing base in opposite direction, thus rotating in the same direction as that of the knob but at slower speed to tighten up or loosen up the screw as desired.